Display apparatus with pixel-aligned ground mesh

ABSTRACT

Display apparatus with reduced susceptibility to electro-magnetic interference includes a display including an array of pixels and a ground mesh located in proximity to the display. The ground mesh includes a plurality of electrically connected ground lines located between the pixels, so that electro-magnetic radiation emitted or received by the display is reduced.

CROSS REFERENCE TO RELATED APPLICATIONS

Reference is made to commonly assigned U.S. patent application Ser. No.13/626,917 filed Sep. 26, 2012, entitled “Display Apparatus WithPixel-Aligned Ground Micro-Wire” by Ronald S. Cok and U.S. patentapplication Ser. No. ______ (K001309) filed concurrently herewith,entitled “Making Display Apparatus With Pixel-Aligned Ground Mesh” byRonald S. Cok, et al, the disclosures of which are incorporated herein.

FIELD OF THE INVENTION

The present invention relates to suppressing electromagneticinterference in a display-and-touch-screen apparatus using aground-plane structure.

BACKGROUND OF THE INVENTION

Transparent conductors are widely used in the flat-panel displayindustry to form electrodes that are used to electrically switchlight-emitting or light-transmitting properties of a display pixel, forexample, in liquid crystal or organic light-emitting diode displays.Transparent conductive electrodes are also used in touch screens inconjunction with displays. In such applications, the transparency andconductivity of the transparent electrodes are important attributes sothat they do not inhibit the visibility of the displays. In general, itis desired that transparent conductors have a high transparency (forexample, greater than 90% in the visible spectrum) and a low electricalresistivity (for example, less than 10 ohms/square).

Touch screens with transparent electrodes are widely used withelectronic displays, especially for mobile electronic devices. Suchdevices typically include a touch screen mounted over an electronicdisplay that displays interactive information. Touch screens mountedover a display device are largely transparent so a user can viewdisplayed information through the touch-screen and readily locate apoint on the touch-screen to touch and thereby indicate the informationrelevant to the touch. By physically touching, or nearly touching, thetouch screen in a location associated with particular information, auser can indicate an interest, selection, or desired manipulation of theassociated particular information. The touch screen detects the touchand then electronically interacts with a processor to indicate the touchand touch location. The processor can then associate the touch and touchlocation with displayed information to execute a programmed taskassociated with the information. For example, graphic elements in acomputer-driven graphic user interface are selected or manipulated witha touch screen mounted on a display that displays the graphic userinterface. Referring to FIG. 20, a prior-art display and touch-screenapparatus 100 includes a display 110 with a corresponding touch screen120 mounted with the display 110 so that information displayed on thedisplay 110 is viewed through the touch screen 120. Graphic elementsdisplayed on the display 110 are selected, indicated, or manipulated bytouching a corresponding location on the touch screen 120. The touchscreen 120 includes a first transparent substrate 122 with firsttransparent electrodes 130 formed in the x dimension on the firsttransparent substrate 122 and a second transparent substrate 126 withsecond transparent electrodes 132 formed in the y-dimension facing thex-dimension first transparent electrodes 130 on the second transparentsubstrate 126. A dielectric layer 124 is located between the first andsecond transparent substrates 122, 126 and first and second transparentelectrodes 130, 132. Referring also to the plan view of FIG. 21, in thisexample first pad areas 128 in the first transparent electrodes 130 arelocated adjacent to second pad areas 129 in the second transparentelectrodes 132. (The first and second pad areas 128, 129 are separatedinto different parallel planes by the dielectric layer 124.) The firstand second transparent electrodes 130, 132 have a variable width andextend in orthogonal directions (for example as shown in U.S. PatentApplication Publication Nos. 2011/0289771 and 2011/0099805). When avoltage is applied across the first and second transparent electrodes130, 132, electric fields are formed between the first pad areas 128 ofthe x-dimension first transparent electrodes 130 and the second padareas 129 of the y-dimension second transparent electrodes 132.

A display controller 142 (FIG. 20) connected through electrical bussconnections 136 controls the display 110 in cooperation with atouch-screen controller 140. The touch-screen controller 140 isconnected through electrical buss connections 136 and wires 134 andcontrols the touch screen 120. The touch-screen controller 140 detectstouches on the touch screen 120 by sequentially electrically energizingand testing the x-dimension first and y-dimension second transparentelectrodes 130, 132.

Referring to FIG. 22, in another prior-art embodiment, rectangular firstand second transparent electrodes 130, 132 are arranged orthogonally onfirst and second transparent substrates 122, 126 with interveningdielectric layer 124, forming touch screen 120 which, in combinationwith the display 110 forms the touch screen 120 and display apparatus100. In this embodiment, first and second pad areas 128, 129 coincideand are formed where the first and second transparent electrodes 130,132 overlap. The touch screen 120 and display 110 are controlled bytouch screen and display controllers 140, 142, respectively, throughelectrical buss connections 136 and wires 134.

Since touch-screens are largely transparent so as not to inhibit thevisibility of the displays over which the touch-screens are located, anyelectrically conductive materials located in the transparent portion ofthe touch-screen either employ transparent conductive materials oremploy conductive elements that are too small to be readily resolved bythe eye of a touch-screen user. Transparent conductive metal oxides arewell known in the display and touch-screen industries and have a numberof disadvantages, including limited transparency and conductivity and atendency to crack under mechanical or environmental stress. This isparticularly problematic for flexible touch-screen-and-display systems.Typical prior-art conductive electrode materials include conductivemetal oxides such as indium tin oxide (ITO) or very thin layers ofmetal, for example silver or aluminum or metal alloys including silveror aluminum. These materials are coated, for example, by sputtering orvapor deposition, and are patterned on display or touch-screensubstrates, such as glass. However, the current-carrying capacity ofsuch electrodes is limited, thereby limiting the amount of power thatcan be supplied to the pixel elements. Moreover, the substrate materialsare limited by the electrode material deposition process (e.g.sputtering). Thicker layers of metal oxides or metals increaseconductivity but reduce the transparency of the electrodes.

Various methods of improving the conductivity of transparent conductorsare taught in the prior art. For example, U.S. Pat. No. 6,812,637describes an auxiliary electrode to improve the conductivity of thetransparent electrode and enhance the current distribution. Suchauxiliary electrodes are typically provided in areas that do not blocklight emission, e.g., as part of a black-matrix structure.

It is also known in the prior art to form conductive traces usingnano-particles including, for example silver. The synthesis of suchmetallic nano-crystals is known. For example, U.S. Pat. No. 6,645,444describes a process for forming metal nano-crystals optionally doped oralloyed with other metals. U.S. Patent Application Publication No.2006/0057502 describes fine wirings made by drying a coated metaldispersion colloid into a metal-suspension film on a substrate,pattern-wise irradiating the metal-suspension film with a laser beam toaggregate metal nano-particles into larger conductive grains, removingnon-irradiated metal nano-particles, and forming metallic wiringpatterns from the conductive grains. However, such wires are nottransparent and thus the number and size of the wires limits thesubstrate transparency as the overall conductivity of the wiresincreases.

Touch-screens including very fine patterns of conductive elements, suchas metal wires or conductive traces are known. For example, U.S. PatentApplication Publication No. 2011/0007011 teaches a capacitive touchscreen with a mesh electrode, as does U.S. Patent ApplicationPublication No. 2010/0026664.

Referring to FIG. 23, a prior-art x- or y-dimension variable-width firstor second transparent electrode 130, 132 includes a micro-pattern 156 ofmicro-wires 150 arranged in a rectangular grid or mesh. The micro-wires150 are multiple very thin metal conductive traces or wires formed onthe first and second transparent substrates 122, 126 (not shown in FIG.23) to form the x- or y-dimension first or second transparent electrodes130, 132. The micro-wires 150 are so narrow that they are not readilyvisible to a human observer, for example 1 to 10 microns wide. Themicro-wires 150 are typically opaque and spaced apart, for example by 50to 500 microns, so that the first or second transparent electrodes 130,132 appear to be transparent and the micro-wires 150 are notdistinguished by an observer.

It is known that micro-wire electrodes in a touch-screen can visiblyinteract with pixels in a display and various layout designs areproposed to avoid such visible interaction. Thus, the pattern ofmicro-wires in a transparent electrode is important for optical as wellas electrical reasons.

A variety of layout patterns are known for micro-wires used intransparent electrodes. U.S. Patent Application Publication2010/0302201, U.S. Patent Application Publication No. 2012/0031746, U.S.Patent Application Publication No. 2012/0162116, and U.S. PatentApplication Publication No. 2011/0291966 teach various micro-wirepatterns used for electrodes in capacitive touch screens. For example,FIG. 24 illustrates first and second orthogonal transparent electrodes130, 132 having a micro-pattern 156 of micro-wires 150 arranged in adiamond pattern.

When in operation, electronic circuits such as those used to controlarrays of pixels in a flat-screen display or to drive electrodes in acapacitive touch screen emit electromagnetic radiation that interfereswith other nearby, electronic devices. For example, the signal lines andtransistors that control the behavior of pixels in a flat-screen displayemit electromagnetic radiation that can interfere with signals in anearby touch screen. Likewise, the electrodes that are controlled tosense capacitance in a capacitive touch screen emit electromagneticradiation that can interfere with signal lines and transistors in anearby flat-screen display. Since touch screens and display devices aretypically laminated together in a thin package, such interference canreduce the signal transmission rate or cause spurious signals in eitheror both of a laminated touch screen and display device.

There is a need, therefore, for an improved method and structure forreducing electromagnetic interference in a touch-screen-and-displayapparatus that does not reduce visibility of the display, is robust inthe presence of mechanical stress, and reduces reflections.

SUMMARY OF THE INVENTION

In accordance with the present invention, display apparatus with reducedsusceptibility to electro-magnetic interference, comprises:

a display including an array of pixels; and

a ground mesh located in proximity to the display, the ground meshincluding a plurality of electrically connected ground lines locatedbetween the pixels, so that electro-magnetic radiation emitted orreceived by the display is reduced.

The present invention provides a display apparatus with reducedelectromagnetic interference that preserves display visibility andprovides mechanical flexibility. The display apparatus can also be usedin combination with a touch screen to reduce electromagneticinterference in both the touch screen and the display.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features and advantages of the present inventionwill become more apparent when taken in conjunction with the followingdescription and drawings wherein identical reference numerals have beenused to designate identical features that are common to the figures, andwherein:

FIG. 1 is an exploded perspective of an embodiment of the presentinvention;

FIGS. 2-4 are plan views of embodiments of the present invention;

FIGS. 5-7 are plan views of embodiments of the present invention havingoffset pixel rows or columns;

FIG. 8 is a cross section of an embodiment of the present invention;

FIGS. 9-10 are exploded cross sections of embodiments of the presentinvention;

FIG. 11 is a cross section of another embodiment of the presentinvention;

FIGS. 12-13 are exploded cross sections of embodiments of the presentinvention;

FIGS. 14-19 are flow diagrams illustrating embodiments of the presentinvention;

FIG. 20 is a prior-art exploded perspective illustrating a prior-artmutual capacitive touch screen having adjacent pad areas in conjunctionwith a display and controllers;

FIG. 21 is a prior-art schematic illustrating prior-art adjacent padareas in a capacitive touch screen;

FIG. 22 is a prior-art exploded perspective illustrating a prior-artmutual capacitive touch screen having overlapping pad areas inconjunction with a display and controllers;

FIG. 23 is a prior-art schematic illustrating prior-art micro-wires inan apparently transparent electrode;

FIG. 24 is a prior-art schematic illustrating prior-art micro-wiresarranged in two arrays of orthogonal transparent electrodes; and

FIG. 25 is a cross section illustrating a two-layer ground lineaccording to an embodiment of the present invention.

The Figures are not drawn to scale since the variation in size ofvarious elements in the Figures is too great to permit depiction toscale.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1 in an embodiment of the present invention, a displayapparatus 10 with reduced susceptibility to electro-magneticinterference includes a display 40 having an array of pixels 20. Aground mesh 50 is located in proximity to the display 40. Ground mesh 50includes a plurality of electrically connected and electricallyconducting ground lines 52 located between pixels 20, so thatelectro-magnetic radiation emitted or received by display 40 is reduced.

Display 40 can be any of various displays 40 known in the art, forexample flat-panel displays such as liquid crystal displays or organiclight-emitting diode displays. The present invention is particularlyuseful in portable computing or communication devices having displays 40incorporating touch screens 30. In a display apparatus 10 including atouch screen 30, ground mesh 50 is located between touch screen 30 anddisplay 40.

Pixels 20 of display 40 can be rectangular or have other shapes and areseparated by inter-pixel gaps in at least one dimension, for examplerows of pixels 20 can be separated by row inter-pixel gaps 24 or columnsof pixels can be separated by column inter-pixel gaps 22, or both. Insuch an arrangement, ground lines 52 are located in the row inter-pixelgaps 24, the column inter-pixel gaps 22, or both the row inter-pixelgaps 24 and the column inter-pixel gaps 22. Pixels 20 are formed in alayer on or over a display substrate 42. The layer can be planar, forexample as is found in rigid displays, or can be flexible.

Ground mesh 50 includes a plurality of electrically inter-connected andelectrically conducting ground lines 52 formed in a layer separate fromthe layer in which the pixels 20 are formed, for example ground mesh 50is above or below the layer in which the pixels 20 are formed. Groundmesh 50 can be formed in a layer or substrate on which touch screen 30or display 40 is formed. The layer can be planar, rigid, or flexible.Ground lines 52 can be rectangular or can have other shapes. Groundlines 52 can be straight or curved and can accommodate differentlyshaped pixels 20. Ground mesh 50 can be an interwoven or intertwinedstructure of electrical conductors (ground lines 52) and can have evenlyspaced and uniform openings between ground lines 52 in which are locatedpixels 20. The ground lines 52 can form a regular structure.Alternatively, ground lines 52 are irregular in shape or distribution.

Ground lines 52 are located between pixels 20 in row or columninter-pixel gaps 24, 22. To be located between pixels 20 means thatground lines 52 projected orthogonally from the layer in which groundlines 52 are formed onto the layer or substrate on which pixels 20 areformed will be located between pixels 20. Projection lines 57 in FIG. 1illustrate the location of ground lines 52 between pixels 20. Thus,light controlled orthogonally from the layer or substrate on whichpixels 20 are formed will pass between ground lines 52 and will not beoccluded or otherwise interfered with by ground lines 52 making upground mesh 50.

A ground line 52 is an electrically conductive wire or trace, forexample made of metal, metal oxides, or micro-wires. Ground mesh 50includes electrically conductive ground lines 52. Ground mesh 50receives ambient electromagnetic radiation, converting the radiationinto electrical current that can be conducted to an apparatus groundsignal. Such radiation can be emitted, for example, by electrodes oractive electronic components such as transistors found in flat-panelactive-matrix displays or by electrodes and conductors found in touchscreens. By receiving and absorbing emitted electromagnetic radiation,ground mesh 50 prevents such radiation from being received by conductiveelements of display 40 or touch screen 30 and reducing the performanceof display 40 or touch screen 30, for example through the production ofspurious electronic signals or increased electrical noise. The effect ofelectromagnetic radiation on electronic equipment such as displays 40and touch screens 30 are known in the art. Therefore, the use of groundmesh 50 enhances the performance of display apparatus 10, display 40, ortouch screen 30.

Ground mesh 50 is located in proximity to display 40. Ground mesh 50 canbe formed on or over display 40, on touch screen 30, or on a separatesubstrate. Ground mesh 50 can be located within a few microns of pixels20, within 10-100 microns of pixels 20, within 100 microns to 1 mm ofpixels 20, or within 1 mm-10 mm of pixels 20, depending on theconstruction of, and the various layers found in, display apparatus 10.It is preferred to locate ground mesh 50 closer rather than farther frompixels 20 in display 40 so as to improve the reception ofelectromagnetic radiation from display 40 by ground mesh 50.Alternatively, it is preferred to locate ground mesh 50 closer ratherthan farther from touch screen 30 so as to improve the reception ofelectromagnetic radiation from touch screen 30 by ground mesh 50. Inanother embodiment, ground mesh 50 is located close to both display 40and touch screen 30, for example between display 40 and touch screen 30.As will be readily apparent to knowledgeable designers, it is alsouseful to locate ground mesh 50 close to pixels 20 of display 40 so thatlight emitted, transmitted, or reflected by pixels 20 is not occluded byground lines 52, particularly for a viewer viewing display 40 from aperpendicular angle or an angle close to perpendicular or from within apre-defined viewing angle.

In an embodiment of the present invention, the ground mesh is locatedcloser to the display 40 than to the touch screen 30. If the frequencyat which signals operate in the display 40 is greater than the frequencyat which signals operate in the touch screen 30, the display 40 canproduce more electro-magnetic interference than is produced by the touchscreen 30. By locating the ground mesh 50 closer to the display 40 thanto the touch screen 30, interference from the display 40 ispreferentially reduced. Alternatively, the ground mesh 50 is locatedcloser to the touch screen 30 than to the display 40, for example if thefrequency at which signals operate in the touch screen 30 is greaterthan the frequency at which signals operate in the display 40, so as topreferentially reduce interference from the touch screen 30.

In an embodiment, ground lines 52 are formed from opaque metal wires orpartially transparent metal oxide traces that conduct electricity. Asillustrated in the plan view of FIG. 2 in an alternative embodiment,ground lines 52 and ground mesh 50 include micro-wires 55. Micro-wires55 are small, electrically connected wires that are individuallyinvisible to the human eye. Since the micro-wires 55 are spaced apart,although electrically connected, for example in a grid or diamondpattern (see FIGS. 23 and 24), a ground line 52 made up of micro-wires55 is relatively transparent, further reducing the perceptibility ofground lines 52 to a viewer of display 40 and reducing any occlusion oflight from pixels 20. A pattern of micro-wires 55 in a ground line 52can be completely independent of a pattern of ground lines 52 or pixels20.

FIG. 2 illustrates ground lines 52 having micro-wires 55 within the rowor column inter-pixel gaps 24, 22 between pixels 20 that do notsubstantially fill the row or column inter-pixel gaps 24, 22. Such adesign reduces the potential occlusion of light controlled by pixels 20,especially when display 40 is viewed at an angle away from theperpendicular, but can also reduce the reception of electromagneticradiation by ground mesh 50. Referring to FIG. 3 in another embodimentof the present invention, ground mesh 50 having micro-wires 55substantially fills the row or column inter-pixel gaps 24, 22 betweenpixels 20. This design can be useful when the ground mesh 50 is close topixels 20, for example formed on a layer above pixels 20.

FIGS. 1, 2, and 3 illustrate identical ground lines 52 of ground mesh 50between every pixel 20. Pixels 20 can be grouped into pixel groups 26,(FIG. 4) for example differently colored pixels such as red, green,blue, and white, and ground lines 52 formed between the pixel groups 26rather than between every pixel 20. Since pixel groups 26 can be laidout as units with different spacing between the pixel groups 26 thanbetween the pixels 20 within a pixel group 26, it can be useful to havea different arrangement of ground lines 52 between pixels 20 in a pixelgroup 26 than between pixel groups 26. As shown in the example of FIG.4, ground lines 52 are present between every other row of pixels 20 andbetween every column of pixels 20. However, the ground lines 52 betweenpixels 20 in pixel groups 26 are relatively narrow, with a width W3narrower than the width W1 of the column ground lines 52 between thepixel groups 26 or the row ground lines 52 having a width W2.Furthermore, the width of the column ground lines 52 with a width W1between the pixel groups 26 are greater than the row ground lines 52having a width W2. Thus, ground lines 52 in the row inter-pixel gaps 24have a different width W2 than the ground lines 52 in the columninter-pixel gaps 22 W1 or W3. Furthermore, the various ground lines 52making up ground mesh 50 can have other different attributes, forexample different composition, materials, structure, layout, or pattern.

The rows and column of pixels 20 illustrated in FIGS. 1-4 are shown instraight lines. However, in other embodiments of the present invention,the rows and columns are arranged so that pixels 20 in rows or columnsare offset with respect to each other so that rows or columns need notbe straight. Likewise, ground lines 52 and micro-wires 55 included inground mesh 50 are shown as straight, but need not be. Referring to FIG.5, alternating rows of pixels 20 are offset and ground lines 52 ofground mesh 50, located between every other column of pixels 20 form acrenellated square wave pattern. In this embodiment, ground lines 52 areonly formed in the column direction. Referring to FIG. 6, alternatingcolumns of pixels 20 are offset and ground lines 52 of ground mesh 50,located between every other row of pixels 20, form a crenellated squarewave pattern. In this embodiment, ground lines 52 are only formed in therow direction. In an embodiment, ground lines 52 of ground mesh 50including micro-wires 55 are located between only a subset of pixels 20,for example every other pixel 20. Referring to FIG. 7, alternatingcolumns of pixels 20 are offset and ground mesh 50 is located betweenboth rows and columns of pixels 20 but does not completely fill the rowor column inter-pixel gaps 24, 22 (not shown).

In a further embodiment of the present invention, and as furtherillustrated in FIG. 1, display 40 can include a display ground 135, forexample a wire connected to a ground signal in display 40, or touchscreen 30 can include a touch-screen ground 137. The display ground 135or touch-screen ground 137 is electrically connected to ground mesh 50,for example through wire 134. Any two or all three of the ground signalscan be electrically connected. By electrically connecting the groundsignals from the ground mesh 50, the display 40, and the touch screen30, either directly or through a controller 90 as illustrated, furtherreduces electrical noise in the display apparatus 10. Ground signals andelectrical connections are well known in the electrical engineeringarts.

In a further embodiment of the present invention, the ground lines 52are black. Materials, for example silver, can form black conductors andare known in the art. In an alternative embodiment of FIG. 25, a secondlight-absorbing layer 54 is formed above or below, or above and below, afirst electrically conducting layer 53 in ground line 52 to absorblight. Such absorption can reduce reflectance from display apparatus 10and improve the contrast of display 40. Other color conductors or lightabsorbers can be used and are known in the art. Light absorbers such ascarbon black, dyes, or pigments can be used.

The components, design, and construction of displays 40, touch screens30, for example capacitive touch screens, are known in the art. Meshstructures of electrically conductive ground wires, ground traces, ormicro-wires formed on a substrate are also known in the art, as is theircontrol and electrical connection. The integration of displays 40, touchscreens 30, and ground mesh 50 structures can be accomplished usingmethods known in the art. Methods of making such structures according tovarious embodiments of the present invention are now discussed in moredetail.

The structure of display apparatus 10 can be constructed using a varietyof methods. Referring first to FIG. 8, a display 40 includes a displaysubstrate 42 having a pixel side 43 and an opposite side 44. Formed onor in display substrate 42 on pixel side 43 are pixels 20, over which aprotective layer 80 is located. Protective layer 80 can be a displaycover 48 laminated over pixels 20 or a protective layer 80 coated overpixels 20. Electrically conductive ground lines 52 are located overprotective layer 80, forming ground mesh 50. Ground lines 52 can beformed on protective layer 80 (e.g. by coating and patterned processingor by patterned deposition) or laminated to protective layer 80. Touchscreen 30 is located over ground mesh 50 and protects ground mesh 50.Light 70 emitted, reflected, or transmitted by pixels 20 passes betweenground lines 52 to a viewer. Thus, in one embodiment according to thepresent invention and also referring to FIG. 14, a method of making adisplay apparatus 10 includes providing 200 a display 40 having an arrayof pixels 20, locating 205 a ground mesh 50 in proximity to the display40, the ground mesh 50 including a plurality of electrically connectedground lines 52 located between the pixels 20, so that electro-magneticradiation emitted or received by the display 40 is reduced. In a furtherembodiment, a touch screen 30 is located 250 over the ground mesh 50.

Referring to FIG. 9, ground lines 52 making up ground mesh 50 can beformed on or laminated to a ground side 32 of a touch screen 30substrate having a touch-screen side 31 and ground side 32. Protectivelayer 80 of display 40 can be a display cover 48 and is laminated totouch screen 30 with ground mesh 50 located between touch screen 30 andpixels 20 with pixels 20 between ground mesh 50 and display substrate42. Alternatively, referring to FIG. 10, ground lines 52 making upground mesh 50 can be formed on a substrate of display 40, for exampleon protective layer 80 or on display cover 48. Ground lines 52 can beformed on display cover 48 before or after display cover 48 (orprotective layer 80) is integrated into display 40. Protective layer 80or display cover 48 is laminated to touch screen 30 with ground mesh 50located between touch screen 30 and pixels 20 with pixels 20 betweenground mesh 50 and display substrate 42. Display cover 48 (or protectivelayer 80) can be laminated to touch screen 30 before or after displaycover 48 or protective layer 80) is integrated into display 40.

In another embodiment (not shown), ground mesh 50 is formed on a groundsubstrate separate from display 40 or touch screen 30. One side of theground substrate can be laminated to display 40 and the other side ofthe ground substrate can be laminated to touch screen 30 in any order orat the same time.

Referring to FIG. 15, pixels 20 are formed 201 on display substrate 42independently of forming 206 ground mesh 50 on a ground substrateseparate from the display 40, display substrate 42, or touch screen 30.The ground substrate is laminated 210 to a display substrate (e.g.either display cover 48 or display substrate 42) and touch screen 30 islaminated 215 over ground mesh 50. The ground substrate is laminated totouch screen 30 before or at the same time that the ground substrate islaminated 210 to a display substrate (e.g. display cover 48 or displaysubstrate 42). The order in which the various substrates are laminatedtogether can vary as will be appreciated by one skilled in the assemblyarts and different orders are included in the present invention.Furthermore, although FIG. 15 describes laminating the various elementstogether, in an alternative embodiment, the elements are sequentiallyformed in layers, for example by coating, patterned deposition,sputtering, or masking and etching as will be discussed further below.

As illustrated in FIGS. 8-10, display 40 is formed on a displaysubstrate 42 having a pixel side 43 on or over which pixels 20 areformed and ground mesh 50 is located on pixel side 43. In an alternativeembodiment illustrated in FIG. 11, display apparatus 10 includes display40 formed on a display substrate 42 having a pixel side 43 on or overwhich the pixels 20 are formed and an opposite side 44. The ground lines52 making up ground mesh 50 are located on opposite side 44, so thatlight 70 controlled by pixel 20 passes through display substrate 42 andtouch screen 30 rather than through display cover 48 (protective layer80).

Referring further to FIG. 12, ground lines 52 making up ground mesh 50are formed on display substrate 42 on opposite side 44 of displaysubstrate 42, so that ground mesh 50 is opposite pixels 20 and displaycover 48 of display 40. Pixels 20 are formed on pixel side 43 of displaysubstrate 42 opposite ground mesh 50 and touch screen 30. Touch screen30 is then located (e.g. by lamination) adjacent to ground mesh 50.Alternatively, referring to FIG. 13, ground lines 52 making up groundmesh 50 are formed on touch screen 30 and located (e.g. by lamination)adjacent display substrate 42 on a side of display substrate 42 oppositepixels 20 and display cover 48 of display 40. In such an embodiment,touch screen 30 is formed on a touch-screen substrate having atouch-screen side 31 and a ground side 32 and ground mesh 50 is providedon ground side 32.

Referring to FIG. 16 in a method of the present invention, pixels 20 areformed 201 on display substrate 42. Ground mesh 50 is formed 207 on orover display substrate 42 and touch screen 30 is located 250 over groundmesh 50. Ground mesh 50 can be formed on or over either pixel side 43 ofdisplay substrate 42 (as illustrated in FIG. 8) or on opposite side 44of display substrate 42 (as illustrated in FIG. 11). Ground mesh 50 canbe formed on or over display substrate 42 (e.g. by coating) or appliedto display substrate 42 (e.g. by lamination). Likewise, touch screen 30can be formed on or over ground mesh 50 (e.g. by coating) or applied toa substrate on which ground mesh 50 is formed (e.g. by lamination).

In an embodiment illustrated in FIG. 17, display 40 is provided 220 andpixels 20 formed 201 on pixel side 43 of display substrate 42.Protective layer 80 is formed 230 on or over pixels 20. Ground mesh 50is formed 235 on or over protective layer 80 and a ground protectivelayer formed 240 on or over ground mesh 50. A ground protective layercan be, for example, display cover 48 or a substrate of touch screen 30.Alternatively, a ground protective layer can be coated or laminated onor over ground mesh 50.

As illustrated in FIG. 18, pixels 20 are formed 201 on display substrate42 and ground mesh 50 formed 255 on display cover 48 (or a protectivelayer 80). Display cover 48 is adhered 260 to display substrate 42 tocomplete display 40. Touch screen 30 is located 250 over ground mesh 50,for example by laminating a touch screen 30 to display 40 or formingtouch screen 30 on display cover 48.

As noted with respect to FIG. 1, as illustrated in FIG. 19 in a methodof the present invention, display 40 is provided 200 and ground mesh 50located 205 in alignment with pixels 20 of display 40. Touch screen 30is located 250 over ground mesh 50 so that ground mesh 50 is betweentouch screen 30 and display 40. A display ground is electricallyconnected 270 to ground mesh 50.

Alternatively or in addition, a touch-screen ground is electricallyconnected 275 to ground mesh 50. The display ground can be electricallyconnected to the touch-screen ground.

The provision of substrates, for example glass, for the construction ofdisplays 40 or various display elements such as pixels 20 or displaycovers 48 are well known, as are method for making displays 40.Likewise, the provision of substrates, for example glass, for theconstruction of touch screens 30 are well known, as are method formaking touch screens 30. Ground mesh 50 can be formed on similarsubstrates or on or over substrates (e.g. display substrate 42 ordisplay cover 48) in display 40 or on or over substrates found in touchscreen 30. Coating methods for forming layers such as protective layer80 or layers of ground lines 52 are known as are lamination methods forlaminating structures together, for example display substrate 42 andtouch screen 30. Methods and materials for forming ground signals indisplays 40 and touch screens 30, and electrically connecting them, forexample with wires, are also known.

The present invention reduces the presence of electromagneticinterference between displays 40 and adjacent touch screens 30 indisplay apparatus 10. Ambient electromagnetic interference from othersources is also reduced. Ground mesh 50 can also provide an anti-staticlayer during handling of touch screen 30 (when formed on a substrate oftouch screen 30) before lamination or integration with display 40.Similarly, ground mesh 50 can provide an anti-static layer duringhandling of display 40 (when formed on a substrate of display 40, e.g.display cover 48 or display substrate 42) before lamination orintegration with touch screen 30.

A touch-screen 30 includes a substrate such as dielectric layer 124located over display 40. Touch screen 30 has row electrodes located on arow side of dielectric layer 124 and column electrodes located on acolumn side of dielectric layer 124 so that row and column electrodesare separated by dielectric layer 124.

Display apparatus 10 of the present invention can be operated by usingdisplay controller 142 (as shown in FIG. 20) to control the display 40to display information with pixels 20, for example by providing powerand signals to pixel electrodes, thin-film transistors, electricalbusses, and passive electrical components such as resistors andcapacitors found in display 40. Touch screen controller 140 (as shown inFIG. 20) provides a voltage differential sequentially to touch screenrow and column electrodes (not shown) to scan the capacitance of thecapacitor array formed where the touch screen row and column electrodesoverlap. Any change in the capacitance of a capacitor in the capacitorarray can indicate a touch at the location of the capacitor in thecapacitor array. The location of the touch can be related to informationpresented on one or more pixels 20 at the corresponding pixel locationto indicate an action or interest in the information present at thecorresponding pixel location.

By providing power and signals to electrodes, transistors, and otherelectrical components in display 40 and energizing the electrodes intouch screen 30, electromagnetic radiation is produced. In the absenceof ground mesh 50, this electromagnetic radiation is then received bythe components in display 40 or touch screen 30 forming spurious signalsor electrical signal noise that can cause the display 40 or touch screen30 to operate incorrectly, at a lower rate (for example reducing refreshor scanning rates), or with less accurate, more noisy, signals.According to the present invention, by locating ground mesh 50 adjacentdisplay 40 or between touch screen 30 and display 40, suchelectromagnetic interference is reduced and display apparatus 10operation is more accurate, less noisy, or has a higher rate with fewererrors.

As will be readily understood by those familiar with the lithographicand display design arts, the terms row and column are arbitrarydesignations of two different, usually orthogonal, dimensions in atwo-dimensional arrangement of pixels on a surface, for example asubstrate surface, and can be exchanged. That is, a row can beconsidered as a column and a column considered as a row simply byrotating the surface ninety degrees with respect to a viewer. Thus, thenomenclature for rows and columns can be exchanged. Being formed on,over, or under a substrate side includes being formed on layers formedon a substrate side. Over and under are relative terms that can beexchanged.

In an embodiment, because micro-wires 55 in ground lines 52 do notsubstantially occlude any light emitted, transmitted, or reflected bypixels 20, ground mesh 50 formed from micro-wires 55 does not interferewith display 40 and, furthermore, can be apparently transparent, thusimproving the visual transparency of a device or device formed with sucha ground mesh 50 and avoiding any visible interaction between groundmesh 50 and light emitted or reflected from display 40 located under orbehind ground mesh 50.

In one embodiment of the present invention, micro-wires 55 are the onlyconductive elements in ground mesh 50. In another embodiment, additionalconductivity is provided to ground mesh 50 by a transparent conductorlocated between pixels 20 in electrical contact with micro-wires 55located in the column and row inter-pixel gaps 22, 24. Transparentconductors can be, for example, a transparent metal oxide conductor(TCO) such as indium tin oxide or aluminum oxide. Furthermore,micro-wires 55 can be black, for example including black silver orhaving a coating of light-absorbing material such as carbon black, adye, or pigment.

Display substrate 42 can have a substantially planar pixel side 43 onwhich pixels 20 are correspondingly located and a substantially planaropposite side 44 opposed to pixel side 43. The pixel and opposite sides43, 44 can be substantially parallel. Pixels 20 are formed on pixel side43 or on one or more layers on pixel side 43. In various embodiments,ground mesh 50 is formed on opposite side 44 or on one or more layers onopposite side 44 before or after pixels 20 are formed on pixel side 43of display substrate 42.

Substrates of the present invention can include any material capable ofproviding a supporting surface on which micro-wires 55 or displayelements can be formed and patterned. Substrates such as glass, metal,or plastics can be used and are known in the art together with methodsfor providing suitable surfaces. In a useful embodiment, substrates aresubstantially transparent, for example, having a transparency of greaterthan 90%, 80% 70% or 50% in the visible range of electromagneticradiation.

Various substrates of the present invention can be similar substrates,for example made of similar materials and having similar materialdeposited and patterned thereon. Likewise, electrodes or ground lines 52of the present invention can be similar, for example made of similarmaterials using similar processes.

Ground lines 52 of the present invention can be formed directly onsubstrates or over substrates or on layers formed on substrates. Thewords “on”, “over”, or the phrase “on or over” indicate that the groundlines 52 or micro-wires 55 of the present invention can be formeddirectly on a substrate, on layers formed on a substrate, or on otherlayers or another substrate located so that the ground lines 52 ormicro-wires 55 are over the desired substrate. Likewise, ground lines 52or micro-wires 55 can be formed under or beneath substrates. The words“on”, “under”, “beneath” or the phrase “on or under” indicate that theground lines 52 or micro-wires 55 of the present invention can be formeddirectly on a substrate, on layers formed on a substrate, or on otherlayers or another substrate located so that the electrodes are under thedesired substrate. “Over” or “under”, as used in the present disclosure,are simply relative terms for layers located on or adjacent to opposingsurfaces of a substrate. By flipping the substrate and relatedstructures over, layers that are over the substrate become under thesubstrate and layers that are under the substrate become over thesubstrate. The descriptive use of “over” or “under” do not limit thestructures of the present invention.

In an embodiment of the present invention, ground lines 52 are variablein width, where the length is the extent of ground line 52 in the lengthdirection over a substrate and the width is in a direction orthogonal tothe length. The width variations can be spatially aligned so that, forexample, one ground line 52 has its narrowest point where an adjacentground line 52 has its widest point or so that one ground line 52 hasits narrowest point where an adjacent ground line 52 has its narrowestpoint.

As used herein, micro-wires 55 in each ground line 52 are micro-wires 55formed in a micro-wire layer that forms a conductive mesh ofelectrically connected micro-wires 55. If a substrate (e.g. displaycover 48, display substrate 42, touch screen 30, or an additionalsubstrate) on which micro-wires 55 are formed is planar, for example, arigid planar substrate such as a glass substrate, the micro-wires 55 ina micro-wire layer are formed in, or on, a common plane as a conductive,electrically connected mesh. If the substrate on which micro-wires 55 isflexible and curved, for example a plastic substrate, the micro-wires 55in a micro-wire layer are a conductive, electrically connected mesh thatis a common distance from a surface of the flexible substrate.

In an example and non-limiting embodiment of the present invention, eachmicro-wire 55 is 5 microns wide and separated from neighboringmicro-wires 55 in a ground line 52 by a distance of 50 microns, so thatthe ground line 52 is 90% transparent. As used herein, transparentrefers to elements that transmit at least 50% of incident visible light,preferably 80% or at least 90%. The micro-wires 55 can be arranged in amicro-pattern that is unrelated to the pattern of the ground lines 52.Micro-patterns other than those illustrated in the Figures can be usedin other embodiments and the present invention is not limited by thepattern of the micro-wires 55 or ground lines 52.

Coating methods for making protective layers are known in the art andcan use, for example, spin or slot coating or extrusion of plasticmaterials on a substrate, or sputtering. Suitable materials are alsowell known. The formation of patterned electrical wires on a substrateare also known, as are methods of making displays, such as OLED orliquid crystal, on a substrate and providing and assembling covers withthe substrate.

Micro-wires 55 can be metal, for example silver, gold, aluminum, nickel,tungsten, titanium, tin, or copper or various metal alloys including,for example silver, gold, aluminum, nickel, tungsten, titanium, tin, orcopper. Other conductive metals or materials can be used. Micro-wires 55can be made of a thin metal layer. Micro-wires 55 can be, but need notbe, opaque. Alternatively, the micro-wires 55 can include cured orsintered metal particles such as nickel, tungsten, silver, gold,titanium, or tin or alloys including nickel, tungsten, silver, gold,titanium, or tin. Conductive inks can be used to form micro-wires 55with pattern-wise deposition and curing steps. Other materials ormethods for forming micro-wires 55 can be employed and are included inthe present invention.

Micro-wires 55 can be formed by patterned deposition of conductivematerials or of patterned precursor materials that are subsequentlyprocessed, if necessary, to form a conductive material. Suitable methodsand materials are known in the art, for example inkjet deposition orscreen printing with conductive inks. Alternatively, micro-wires 55 canbe formed by providing a blanket deposition of a conductive or precursormaterial and patterning and curing, if necessary, the deposited materialto form a micro-pattern of micro-wires 55. In another embodiment,micro-wires 55 can be formed by embossing trenches in a substrate (forexample in an uncured or partially cured layer of resin and then curingthe resin) and filling the trenches with a conductive material. Theground mesh 50 can be calendared to make the lines thinner therebyreducing the reflected light and improving off-axis optical performance.

Photo-lithographic and photographic methods are known to perform suchprocessing. The present invention is not limited by the micro-wirematerials or by methods of forming a pattern of micro-wires 55 on asupporting substrate surface. Commonly-assigned U.S. Ser. No. 13/406,649filed Feb. 28, 2012, the disclosure of which is incorporated herein,discloses a variety of materials and methods for forming patternedmicro-wires on a substrate surface.

In embodiments of the present invention, the micro-wires 55 are made bydepositing an unpatterned layer of material and then differentiallyexposing the layer to form the different micro-wire micro-patterns. Forexample, a layer of curable precursor material is coated over thesubstrate and pattern-wise exposed. The first and second micro-patternsare exposed in a common step or in different steps. A variety ofprocessing methods can be used, for example photo-lithographic or silverhalide methods. The materials can be differentially pattern-wise exposedand then processed.

A variety of materials can be employed to form the patterned micro-wires55, including resins that can be cured by cross-linkingwave-length-sensitive polymeric binders and silver halide materials thatare exposed to light. Processing can include both washing out residualuncured materials and curing or exposure steps.

In an embodiment, a precursor layer includes conductive ink, conductiveparticles, or metal ink. The exposed portions of the precursor layer canbe cured to form the micro-wires 55 (for example by exposure topatterned laser light to cross-link a curable resin) and the uncuredportions removed. Alternatively, unexposed portions of the first andsecond micro-wire layers can be cured to form the micro-wires 55 and thecured portions removed.

In another embodiment of the present invention, the precursor layers aresilver salt layers. The silver salt can be any material that is capableof providing a latent image (that is, a germ or nucleus of metal in eachexposed grain of metal salt) according to a desired pattern uponphoto-exposure. The latent image can then be developed into a metalimage. For example, the silver salt can be a photosensitive silver saltsuch as a silver halide or mixture of silver halides. The silver halidecan be, for example, silver chloride, silver bromide, silverchlorobromide, or silver bromoiodide.

According to some embodiments, the useful silver salt is a silver halide(AgX) that is sensitized to any suitable wavelength of exposingradiation. Organic sensitizing dyes can be used to sensitize the silversalt to visible or IR radiation, but it can be advantageous to sensitizethe silver salt in the UV portion of the electromagnetic spectrumwithout using sensitizing dyes.

Processing of AgX materials to form conductive traces typically involvesat least developing exposed AgX and fixing (removing) unexposed AgX.Other steps can be employed to enhance conductivity, such as thermaltreatments, electroless plating, physical development, and variousconductivity-enhancing baths, as described in U.S. Pat. No. 3,223,525.

To achieve transparency, the total area occupied by the micro-wires 55can be less than 15% of the ground lines 52.

In an embodiment, the first and second precursor material layers caneach include a metallic particulate material or a metallic precursormaterial, and a photosensitive binder material.

In any of these cases, the precursor material is conductive after it iscured and any needed processing completed. Before patterning or beforecuring, the precursor material is not necessarily electricallyconductive. As used herein, precursor material is material that iselectrically conductive after any final processing is completed and theprecursor material is not necessarily conductive at any other point inthe micro-wire formation process.

Methods and devices for forming and providing substrates, coatingsubstrates, patterning coated substrates, or pattern-wise depositingmaterials on a substrate are known in the photo-lithographic arts.Likewise, tools for laying out electrodes, conductive traces, andconnectors are known in the electronics industry as are methods formanufacturing such electronic system elements. Hardware controllers forcontrolling touch screens and displays and software for managing displayand touch screen systems are well known. These tools and methods can beusefully employed to design, implement, construct, and operate thepresent invention. Methods, tools, and devices for operating capacitivetouch screens can be used with the present invention.

Although the present invention has been described with emphasis oncapacitive touch screen embodiments, the ground mesh 50 of the presentinvention is useful in a wide variety of electronic devices. Suchdevices can include, for example, photovoltaic devices, OLED displaysand lighting, LCD displays, plasma displays, inorganic LED displays andlighting, electrophoretic displays, electrowetting displays, dimmingmirrors, smart windows, transparent radio antennae, transparent heatersand other touch screen devices such as resistive touch screen devices.

The invention has been described in detail with particular reference tocertain embodiments thereof, but it will be understood that variationsand modifications can be effected within the spirit and scope of theinvention.

PARTS LIST

-   W1 ground line width-   W2 ground line width-   W3 ground line width-   10 display apparatus-   20 pixel-   22 column inter-pixel gap-   24 row inter-pixel gap-   26 pixel group-   30 touch screen-   31 touch screen side-   32 ground side-   40 display-   42 display substrate-   43 pixel side-   44 opposite side-   48 display cover-   50 ground mesh-   52 ground line-   53 electrically conductive layer-   54 light-absorbing layer-   55 micro-wire-   57 projection-   70 light-   80 protective layer-   90 controller-   100 display and touch screen apparatus-   110 display-   120 touch screen-   122 first transparent substrate-   124 dielectric layer-   126 second transparent substrate-   128 first pad area-   129 second pad area-   130 first transparent electrode-   132 second transparent electrode-   134 wires-   135 display ground-   136 electrical buss connections-   137 touch-screen ground-   140 touch-screen controller-   142 display controller-   150 micro-wire-   156 micro-pattern-   200 provide display step-   201 form pixels on display substrate step-   205 locate ground mesh step-   206 form ground mesh on ground substrate-   207 form ground mesh on display substrate-   210 laminate ground substrate to display substrate step-   215 laminate touch screen over ground mesh step-   220 provide display substrate step-   230 form protective layer over pixels step-   235 form ground mesh step-   240 form protective layer over ground mesh step-   250 locate touch screen over ground mesh step-   255 form ground mesh on display cover step-   260 adhere display cover to display substrate step-   270 connect ground mesh to display ground step-   275 connect ground mesh to touch-screen ground step

1. Display apparatus with reduced susceptibility to electro-magneticinterference, comprising: a display including an array of pixels; and aground mesh located in proximity to the display, the ground meshincluding a plurality of electrically connected ground lines locatedbetween the pixels, so that electro-magnetic radiation emitted orreceived by the display is reduced.
 2. The display apparatus of claim 1,wherein the ground lines are in a common layer.
 3. The display apparatusof claim 2, wherein the ground lines are in a common plane.
 4. Thedisplay apparatus of claim 1, wherein the ground lines are metal wiresor metal traces.
 5. The display apparatus of claim 1, wherein the groundlines are micro-wires.
 6. The display apparatus of claim 1, wherein theground lines are opaque.
 7. The display apparatus of claim 1, whereinthe ground lines form an interwoven or intertwined structure.
 8. Thedisplay apparatus of claim 1, wherein the ground lines form anarrangement of electrical conductors spaced apart by regular, uniformopenings.
 9. The display apparatus of claim 1, wherein the pixels areseparated by inter-pixel gaps in at least one dimension and the groundlines are located in the inter-pixel gaps.
 10. The display apparatus ofclaim 9, wherein the ground lines substantially fill the inter-pixelgaps.
 11. The display apparatus of claim 9, wherein the ground lines donot substantially fill the inter-pixel gaps so that the ground lines donot occlude light controlled by the pixels when viewed by a user withina pre-defined viewing angle.
 12. The display apparatus of claim 9,wherein the pixels are arranged in rows and columns, the rows of pixelsseparated by row inter-pixel gaps, the columns of pixels separated bycolumn inter-pixel gaps, and the ground lines are located in the rowinter-pixel gaps, the column inter-pixel gaps, or both the rowinter-pixel gaps and the column inter-pixel gaps.
 13. The displayapparatus of claim 12, wherein the ground lines in the row inter-pixelgaps have a different width than the ground lines in the columninter-pixel gaps.
 14. The display apparatus of claim 1, wherein thedisplay further includes a display ground and the ground mesh iselectrically connected to the display ground.
 15. The display apparatusof claim 1, further including a touch screen located in proximity to theground mesh and wherein the ground mesh is located between the touchscreen and the display.
 16. The display apparatus of claim 1, whereinthe touch screen further includes a touch screen and a touch-screenground and the ground mesh is electrically connected to the touch-screenground.
 17. The display apparatus of claim 16, wherein the displayfurther includes a display ground and the ground mesh is electricallyconnected to the display ground and to the touch-screen ground.
 18. Thedisplay apparatus of claim 12, wherein the display is located within 1mm of the ground mesh.
 19. The display apparatus of claim 12, whereinthe ground lines are black.
 20. The display apparatus of claim 12,wherein the ground lines are colored.
 21. The display apparatus of claim12, wherein the ground lines include a first electrically conductivelayer and a second light-absorbing layer.